Fix data race on CpuProfiler::running_

src/cpu-profiler.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/cpu-profiler-inl.h"
 
 #include "src/compiler.h"
 #include "src/frames-inl.h"
 #include "src/hashmap.h"
 #include "src/log-inl.h"
 #include "src/vm-state-inl.h"
 
 #include "include/v8-profiler.h"
 
 namespace v8 {
 namespace internal {
 
 static const int kProfilerStackSize = 64 * KB;
 
 
-ProfilerEventsProcessor::ProfilerEventsProcessor(
-    ProfileGenerator* generator,
-    Sampler* sampler,
-    base::TimeDelta period)
+ProfilerEventsProcessor::ProfilerEventsProcessor(ProfileGenerator* generator,
+                                                 Sampler* sampler,
+                                                 base::TimeDelta period)
     : Thread(Thread::Options("v8:ProfEvntProc", kProfilerStackSize)),
       generator_(generator),
       sampler_(sampler),
-      running_(true),
+      running_(1),
       period_(period),
-      last_code_event_id_(0), last_processed_code_event_id_(0) {
-}
+      last_code_event_id_(0),
+      last_processed_code_event_id_(0) {}
 
 
 void ProfilerEventsProcessor::Enqueue(const CodeEventsContainer& event) {
   event.generic.order = ++last_code_event_id_;
   events_buffer_.Enqueue(event);
 }
 
 
 void ProfilerEventsProcessor::AddCurrentStack(Isolate* isolate) {
   TickSampleEventRecord record(last_code_event_id_);
   RegisterState regs;
   StackFrameIterator it(isolate);
   if (!it.done()) {
     StackFrame* frame = it.frame();
     regs.sp = frame->sp();
     regs.fp = frame->fp();
     regs.pc = frame->pc();
   }
   record.sample.Init(isolate, regs);
   ticks_from_vm_buffer_.Enqueue(record);
 }
 
 
 void ProfilerEventsProcessor::StopSynchronously() {
-  if (!running_) return;
-  running_ = false;
+  if (!base::NoBarrier_AtomicExchange(&running_, 0)) return;
   Join();
 }
 
 
 bool ProfilerEventsProcessor::ProcessCodeEvent() {
   CodeEventsContainer record;
   if (events_buffer_.Dequeue(&record)) {
     switch (record.generic.type) {
 #define PROFILER_TYPE_CASE(type, clss)                          \
       case CodeEventRecord::type:                               \
@@ skipping 30 matching lines @@
   if (record->order != last_processed_code_event_id_) {
     return FoundSampleForNextCodeEvent;
   }
   generator_->RecordTickSample(record->sample);
   ticks_buffer_.Remove();
   return OneSampleProcessed;
 }
 
 
 void ProfilerEventsProcessor::Run() {
-  while (running_) {
+  while (!!base::NoBarrier_Load(&running_)) {
     base::ElapsedTimer timer;
     timer.Start();
     // Keep processing existing events until we need to do next sample.
     do {
       if (FoundSampleForNextCodeEvent == ProcessOneSample()) {
         // All ticks of the current last_processed_code_event_id_ are
         // processed, proceed to the next code event.
         ProcessCodeEvent();
       }
     } while (!timer.HasExpired(period_));
@@ skipping 378 matching lines @@
     ReportBuiltinEventRecord* rec = &evt_rec.ReportBuiltinEventRecord_;
     Builtins::Name id = static_cast<Builtins::Name>(i);
     rec->start = builtins->builtin(id)->address();
     rec->builtin_id = id;
     processor_->Enqueue(evt_rec);
   }
 }
 
 
 } }  // namespace v8::internal